Listen to the voice of experience: there’s no such thing as a step-Grandfather; you are a Grampa, plain and simple. Revel in it.

The little ones will learn to call you Grampa B (or maybe Tall Grampa) to distinguish you from all their other Grampas; but they’ll be just as happy to accept cookies from you as from the rest of the crowd of grampas — biological, adoptive, or marital. To a grandkid, we’re all the same.

Words like “step-Grandfather” are spoken by the same howling idiots who say “You wouldn’t understand, you have no kids of your own” as if it’s easier to raise somebody else’s kids as if they were your own flesh and blood than it is actually to raise your own flesh and blood kids. It’s not easier, it’s harder, as those of us with clues know damned well.

Mitch, you EARNED the title of Grampa the same way the rest of us did – by raising someone as your own child till they proudly presented you with kids of their own. Don’t let anybody water down your victory!